Gene Increases HIV Risk

New research shows a variant of a gene found only in people of African ancestry increases the odds of becoming infected with HIV. However, the same variant also seems to keep the disease from progressing, allowing patients who carry it to live about two years longer.

"It's well-known that individuals vary in their susceptibility to HIV and that after infection occurs, the disease progresses at variable rates," study author Sunil Ahuja from the South Texas Veterans Health Care System, was quoted as saying. "The mystery of variable infection and progression was originally thought to be mainly the result of viral characteristics, but in recent years it has become evident that there is a strong host genetic component."

Researchers say if the new findings can be extrapolated to Africa, where about 90 percent of all people carry the variant, they estimate it may be responsible for 11 percent of the HIV cases there.

The gene -- called Duffy Antigen Receptor for Chemokines (DARC) -- encodes a protein found mainly at the surface of red blood cells. It leaves its carriers without this particular red blood cell receptor. The condition is known as "DARC-negative" and has been well studied because it also protects against infection by a malaria parasite known as Plasmodium vivax. Researchers say it's possible something that protected people against malaria in the past now makes them more susceptible to HIV.

SOURCE: Cell Host & Microbe, 2008

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